Chemotherapy is a potent weapon in the clinical treatment of cancer. Unfortunately, most antitumor agents are associated with serious side effects such as severe gastrointestinal and bone marrow toxicity. This characteristic is due in large part to the lack of selectivity of these highly toxic drugs for the target tumor cells over normal cells. Therefore, the design of either targeted drugs or effective drug delivery vehicles is crucial to advancing cancer chemotherapy. This proposal seeks to develop a novel and general strategy for the site-specific delivery of antineoplastic therapeutics that will rely on the design and optimization of targeted catalytic antibodies (CAbs) for the site- specific release of carbamate prodrugs of antitumor agents. Initial model studies will concentrate on the delivery of the well characterized antineoplastic agents 5-fluorouridine (FUDR) and cytosine arabanoside (ara-C). Methods developed during these investigations will be applicable for the future delivery of existing and future chemotherapeutics. The objectives of this proposal are: l. To design and synthesize: a) aromatic amino acid carbamate prodrugs of FUDR and ara-C, and b) phosporamidate haptens capable of generating CAbs that will activate aromatic amino acid carbamate prodrugs of FUDR and ara-C. 2. To generate as bacteriophage fusion proteins: a) murine antibody libraries from mice immunized with phosphoramidate haptens, and b) human antibody libraries from naive peripheral B-lymphocytes. 3. To generate CAbs from an antibody bacteriophage library by: a) identifying active catalysts with a chromogenic agar plate assay, b) the bacterial expression of CAbs, and c) kinetically characterizing the efficacy of the purified CAbs. 4. To construct bispecific catalytic antibodies capable of binding the surface displayed transferrin receptor of human carcinomas in vitro. 5. To evaluate the ability of bispecific catalytic antibodies in combination with carbamate prodrugs of FUDR or ara-C to inhibit the growth of human carcinomas in vitro that surface display the transferrin receptor.